On Tue, Aug 18, 2020 at 11:17:56AM +0100, Chris Down wrote: > I'd ask that you understand a bit more about the tradeoffs and intentions of > the patch before rushing in to declare its failure, considering it works > just fine :-) > > Clamping the maximal time allows the application to take some action to > remediate the situation, while still being slowed down significantly. 2 > seconds per allocation batch is still absolutely plenty for any use case > I've come across. If you have evidence it isn't, then present that instead > of vague notions of "wrongness". There is no feedback from the freeing rate, therefore it cannot be correct in maintaining a maximum amount of pages. 0.5 pages / sec is still non-zero, and if the free rate is 0, you'll crawl across whatever limit was set without any bounds. This is math 101. It's true that I haven't been paying attention to mm in a while, but I was one of the original authors of the I/O dirty balancing, I do think I understand how these things work.
